A novel method for extending the frequency frontier in gravitational wave observations is proposed. It is shown that gravitational waves can excite a magnon. Thus, gravitational waves can be probed ...by a graviton–magnon detector which measures resonance fluorescence of magnons. Searching for gravitational waves with a wave length
λ
by using a ferromagnetic sample with a dimension
l
, the sensitivity of the graviton–magnon detector reaches spectral densities, around
5.4
×
10
-
22
×
(
l
λ
/
2
π
)
-
2
Hz
-
1
/
2
at 14 GHz and
8.6
×
10
-
21
×
(
l
λ
/
2
π
)
-
2
Hz
-
1
/
2
at 8.2 GHz, respectively.
We have developed an analog front-end electronics, called LTARS20181, for TPC-applications, targeted at dual-phase liquid argon TPCs for neutrino experiments and negative-ion
μ
- TPCs for directional ...dark matter searches. This electronics have a wide dynamic range for input charge up to 1600 fC and a function to output a signal with an appropriate time constant for signals having various peaking times, these unique properties may make the LTARS2018 multi-purpose. In this paper we will report results of the LTARS2018 performance check at room temperature and liquid argon temperature. In addition, we discuss the design concept and characteristics of a new electronics (LTARS2020) that been modified to improve performance in liquid argon.
Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or ...brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that "Electron Tracking Compton Camera" (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics.
Directional information in the direct dark matter searches is believed to be able providing a clear discovery of the galactic WIMP dark matter, together with a further potential to investigate the ...properties of the dark matter. CYGNUS is a concept to detect the galactic WIMP dark matter particles with directionality. In this paper, physics motivation and technological R&D status will be reviewed.
It is an on-going challenge to verify the proton range in situ during proton therapy. Since the protons stop in target tissue, measurement of gamma-rays emitted either promptly from nuclear ...de-excitation or in pair from positron annihilation is the feasible method to monitor the proton range in-vivo. Using the technique of gamma collimation, we empirically demonstrated that the proton range and prompt gamma distribution are well correlated in the therapy energy range, and that measuring prompt gammas is a viable method for the clinical application. However, this collimation technique appears not to be applicable to passively scattered proton beams. The device chosen for gamma imaging in 2D is an electron tracking Compton camera, which images single-emission photons employing a gas chamber to induce Compton scattering. Images of prompt gammas were attained at the proton beam energy of 140 MeV. Measurements showed that gamma image in the energy range of 800–2000 keV provides a better match with the proton range compared to the image by lower energy gammas.
► The prompt gamma measurement is a viable modality to monitor the proton dose range. ► Collimator was used to show correlation between gamma and proton dose distributions. ► Collimation method may not be used for passively scattered proton beams. ► Electron tracking Compton camera can be a practical device for imaging gammas in 2D. ► An optimal gamma energy range for imaging could be found for a given Compton camera.
An α-ray imaging chamber has been developed based on a gaseous micro-time-projection chamber with a low-α emission μ-PIC in a low radioactivity structure. The detector offers the advantage of ...position sensitivity, which allows to image the α-ray contamination for the sample. It measures the α-ray rate in the sample region and a background region at the same time, thus that the net α rate from the sample can be evaluated efficiently by subtracting these rates from each other. In this work, the measurement results for several samples using the detector is provided.
An application of a modern noble pixel detector, XRPIX series, for solar KSVZ axion search experiment is being developed. A low radioactive background is necessary in the detector volume for the ...axion search. We surveyed the radioactivity of all peripheral components mounted on the detector using an HPGe detector. The results are used as an input for a GEANT4 Monte Carlo simulation to study the background in the experiment. This paper describes the expected background and the simulated sensitivity of stacked XRPIX detector currently under development.
To search for neutrinoless double beta decay, we have started developing a high pressure xenon gas time projection chamber as the AXEL (A Xenon ElectroLuminescence detector) project since 2014. We ...proposed a new scheme to measure energy deposit using electroluminescence lights to achieve high energy resolution, large mass and strong background rejection power. Important performances of compositions of our new readout scheme are shown: electric field simulation, VUV sensitivity of MPPC in high pressure gaseous xenon, response of MPPC for large amount of photons. To demonstrate as a whole system, we constructed a small prototype detector using 64 MPPCs filled with 4bar xenon gas. Result of measurement with a 57Co gamma-ray source are shown.
Ambient neutrons are one of the most serious backgrounds for underground experiments in search of rare events. The ambient neutron flux in an underground laboratory of Kamioka Observatory was ...measured using a 3He proportional counter with various moderator setups. Since the detector response largely depends on the spectral shape, the energy spectra of the neutrons transported from the rock to the laboratory were estimated by Monte-Carlo simulations. The ratio of the thermal neutron flux to the total neutron flux was found to depend on the thermalizing efficiency of the rock. Thus, the ratio of the count rate without a moderator to that with a moderator was used to determine this parameter. Consequently, the most-likely neutron spectrum predicted by the simulations for the parameters determined by the experimental results was obtained. The result suggests an interesting spectral shape, which has not been indicated in previous studies. The total ambient neutron flux is (23.5±0.7stat.−2.1+1.9sys.)×10−6cm−2s−1 1. In this paper, we explain our method of the result and discuss our future plan.
PDF
